Thin-film nano-structured materials offer the potential to enhance the performance of thermoelectrics, with near-term capabilities like small-footprint coolers for lasers and microprocessors. Our recent focus has been to transition the enhanced figure-of-merit (ZT) in p-type Bi2Te3/Sb2Te3 and n-type Bi2Te3/Bi2Te3-xSex superlattices to performance at the module level with several device demonstrations. We have been able to obtain a best ZT of ∼2 in a p-n couple, the fundamental cooling or power conversion unit in an operational module. In addition, we have been able to demonstrate p-n couple ZT of as much as 1.6 from heat-to-power efficiency data. The thermal interface resistances between the active device and the external heat source have been optimized. A power level of 38 mW per couple for a ΔT of about 107K, with 4-micron-thick element, was obtained. This translates to an active power density of ∼54 W/cm2 and a mini-module power density of ∼10.5 W/cm2. In short, power devices with thin-film superlattices are a real possibility. In the cooling arena, we have been able to obtain over 50K active cooling with thin-film modules, useable in several laser and microprocessor cooling needs. This is in spite of severe thermal management issues that had to be overcome noting that the “true” hot-side temperature, and hence the “true” ΔT, across the device are much higher. Even so, we have p-n superlattice couples that show twice the cooling ΔTmax, compared to the best bulk p-n couples at cryogenic temperatures. Some of the challenges that remain to be addressed in the full development of this materials technology and thoughts on further progress in nano-structured materials are presented.

This paper discloses the recent developments of high efficiency quantum well thermoelectrics at Hi-Z Technology, Inc. The performance of the latest P type B4C/B9C- N-type Si/SiGe couple will be presented as well as data for the new N-type Si/SiC that will replace Si/SiGe and improve couple efficiency.

Preliminary calculations regarding the development of actual quantum well modules will be presented for power prediction. These modules can be used in future energy conversion system as well as air conditioning system designs.

Our current efforts to produce quantum well films more rapidly will be discussed.